The mechanical loading and muscle activation of four common exercises used in osteoporosis prevention for early postmenopausal women

High impact exercise can reduce postmenopausal bone loss, however stimulus frequency (loading cycles per second) can affect osteogenesis. We aimed to examine the effect of stimulus frequency on the mechanical loading of four common osteoporosis prevention exercises, measuring body acceleration and muscle activation with accelerometry and electromyography (EMG), respectively. Fourteen early postmenopausal women completed randomised countermovement jumps (CMJ), box-drops (BD), heel-drops (HD) and stamp (STP) exercises for continuous and intermittent stimulus frequencies. Sacrum accelerometry and surface electromyography (EMG) of four muscles were recorded. CMJ (mean ± SD: 10.7 ± 4.8 g & 10.0 ± 5.0 g), BD (9.6 ± 4.1 g & 9.5 ± 4.0 g) and HD (7.3 ± 3.8 g & 8.6 ± 4.4 g) conditions generated greater peak acceleration than STP (3.5 ± 1.4 g & 3.6 ± 1.7 g) across continuous and intermittent trials. CMJ and BD generated greater acceleration gradients than STP across continuous and intermittent trials. CMJ generated greater rectus femoris EMG than all other exercises, CMJ and BD generated greater semitendinosus and tibialis anterior EMG than HD across continuous and intermittent trials. CMJ and BD provide greater peak acceleration than STP and remain similar during different stimulus frequencies. CMJ, BD and HD may exceed STP in maintaining postmenopausal bone health.

Genetic diversity and cultivar variants in the NCGR cranberry (Vaccinium macrocarpon Aiton) collection

The American cranberry (Vaccinium macrocarpon) is an endemic domesticated species that has become an economically important commercial fruit crop. The USDA-ARS National Clonal Germplasm Repository (NCGR) houses the national Vaccinium collection, which includes representatives of historical cranberry cultivars and wild-selected germplasm. The objective of this study wasto examine the genotypes of 271 cranberry plants from 77 accessions representing 66 named cultivars using 12 simple-sequence repeats to assess clonal purity and cultivar relatedness. Using principal components analysis and neighbour-joining based on estimated genetic distances between individuals, we identified 64 unique genotypes and observed that intracultivar variants (i.e. subclones) existed in the germplasm collection and in the commercial bogs where some accessions originated. Finally, through a comparison of the genotypes of this study with the previous studies, pedigree analysis and the study of the geographic distribution of cranberry diversity, we identified consensus genotypes for many accessions and cultivars. We highlight the important role that the NCGR collection playsfor ex situ conservation of cranberry germplasm for future breeders and researchers. The NCGR continues to search for historically relevant cultivars absent from the collection in an effort to preserve these genotypes before they are lost and no longer commercially grown.

Biomechanical properties of adjustable extracortical graft fixations in ACL reconstruction

Background

Reliable biomechanical data about the strength of different tibial extracortical graft fixation devices is sparse. This biomechanical study compares the properties of tibial graft fixation in ACL reconstruction with either the ACL Tight Rope™ or the Rigid Loop Adjustable™ device. The hypothesis was that both fixation devices would provide comparable results concerning gap formation during cyclic loading and ultimate failure load.

Methods

Sixteen sawbone tibiae (Sawbones™) underwent extracortical fixation of porcine flexor digitorum profundus grafts for ACL reconstruction. Either the ACL Tight Rope™ (Arthrex) or the Rigid Loop Adjustable™ (DePuy Mitek) fixation device were used, resulting in 2 groups with 8 specimens per group. Biomechanical analysis included pretensioning the constructs 10 times with 0.75 Hz, then cyclic loading of 1,000 position-controlled cycles and 1,000 force-controlled cycles applied with a servohydraulic testing machine. Elongation during cyclic loading was recorded. After this, ultimate failure load and failure mode analysis were performed.

Results

No statistically significant difference could be noted between the groups regarding gap formation during cyclic loading (4.6 ± 2.6 mm for the Rigid Loop Adjustable™ vs. 6.6 ± 1.5 mm for the ACL Tight Rope™ (p > 0.05)), and ultimate failure loads (980 ± 101.9 N for the Rigid Loop Adjustable™ vs. 861 ± 115 N ACL Tight Rope™ (p > 0.05)).

Conclusion

ACL Tight Rope™ and the Rigid Loop Adjustable™ fixation devices yield comparable biomechanical results for tibial extracortical graft fixation in ACL reconstruction. These findings may be of relevance for the future surgical decision-making in ACL reconstruction. Randomized controlled clinical trials comparing both fixation devices are desirable for the future.

Membrane potential oscillations are not essential for spontaneous firing generation in L4 Aβ-afferent neurons after L5 spinal nerve axotomy and are not mediated by HCN channels

NEW FINDINGS

What is the central question of this study? Is spontaneous activity (SA) in L4 dorsal root ganglion (DRG) neurons induced by L5 spinal nerve axotomy associated with membrane potential oscillations in these neurons, and if so, are these membrane oscillations mediated by HCN channels? What is the main finding and its importance? Unlike injured L5 DRG neurons, which have been shown to be incapable of firing spontaneously without membrane potential oscillations, membrane potential oscillations are not essential for SA generation in conducting 'uninjured' L4 neurons, and they are not mediated by HCN channels. These findings suggest that the underlying cellular mechanisms of SA in injured and 'uninjured' DRG neurons induced by spinal nerve injury are distinct.

ABSTRACT

The underlying cellular and molecular mechanisms of peripheral neuropathic pain are not fully understood. However, preclinical studies using animal models suggest that this debilitating condition is driven partly by aberrant spontaneous activity (SA) in injured and uninjured dorsal root ganglion (DRG) neurons, and that SA in injured DRG neurons is triggered by subthreshold membrane potential oscillations (SMPOs). Here, using in vivo intracellular recording from control L4-DRG neurons, and ipsilateral L4-DRG neurons in female Wistar rats that had previously undergone L5 spinal nerve axotomy (SNA), we examined whether conducting 'uninjured' L4-DRG neurons in SNA rats exhibit SMPOs, and if so, whether such SMPOs are associated with SA in those L4 neurons, and whether they are mediated by hyperpolarization-activated cyclic nucleotide gated (HCN) channels. We found that 7 days after SNA: (a) none of the control A- or C-fibre DRG neurons showed SMPOs or SA, but 50%, 43% and 0% of spontaneously active cutaneous L4 Aβ-low threshold mechanoreceptors, Aβ-nociceptors and C-nociceptors exhibited SMPOs, respectively, in SNA rats with established neuropathic pain behaviors; (b) neither SMPOs nor SA in L4 Aβ-neurons was suppressed by blocking HCN channels with ZD7288 (10 mg kg^-1 , i.v.); and (c) there is a tendency for female rats to show greater pain hypersensitivity than male rats. These results suggest that SMPOs are linked to SA only in some of the conducting L4 Aβ-neurons, that such oscillations are not a prerequisite for SA generation in those L4 A- or C-fibre neurons, and that HCN channels are not involved in their electrogenesis.

Prospective real-world analysis of OnabotulinumtoxinA in chronic migraine post-National Institute for Health and Care Excellence UK technology appraisal

BACKGROUND AND PURPOSE

The National Institute for Health and Care Excellence (NICE) in the UK recommends the use of OnabotulinumtoxinA (BoNTA, Botox^® ) in the management of chronic migraine (CM) following specific guidelines within the National Health Service. In view of the lack of data on the efficacy of this therapy following implementation of these guidelines in clinical practice and on the evaluation of guidance compliance, we aimed to evaluate the effectiveness and safety of BoNTA in patients with CM following the NICE guidelines.

METHODS

This was a prospective real-life audit study.

RESULTS

After two treatments, 127 of 200 patients (63.5%) obtained at least a 30% reduction in headache days. Those who continued the treatment up to 3 years reported a stable beneficial effect compared with baseline. Amongst responders, 68 patients (53.5%) were reclassified as episodic migraineurs. A total of 57 of these patients (83.8%) converted to an episodic migraine pattern at 6-month follow-up. The majority of those whose migraine became episodic after BoNTA extended the treatment intervals beyond 3 months (range 4-8 months) before noticing any worsening of headache. We observed no significant differences in the efficacy measures in patients treated with 155 U BoNTA compared with those treated with >155 U BoNTA.

CONCLUSIONS

When administered according to the NICE guidance, BoNTA produced a clinically meaningful effect in the long-term management of CM with and without medication overuse headache. Treatment discontinuation when CM becomes episodic may be useful in clinical practice to identify those who may benefit from extended treatment intervals. Our clinical experience indicates a lack of additional benefit from using the 'follow-the-pain' paradigm.

ICRP Publication 134: Occupational Intakes of Radionuclides: Part 2

Abstract –

The 2007 Recommendations of the International Commission on Radiological Protection (ICRP, 2007) introduced changes that affect the calculation of effective dose, and implied a revision of the dose coefficients for internal exposure, published previously in the Publication 30 series (ICRP, 1979, 1980, 1981, 1988b) and Publication 68 (ICRP, 1994b). In addition, new data are available that support an update of the radionuclide-specific information given in Publications 54 and 78 (ICRP, 1988a, 1997b) for the design of monitoring programmes and retrospective assessment of occupational internal doses. Provision of new biokinetic models, dose coefficients, monitoring methods, and bioassay data was performed by Committee 2, Task Group 21 on Internal Dosimetry, and Task Group 4 on Dose Calculations. A new series, the Occupational Intakes of Radionuclides (OIR) series, will replace the Publication 30 series and Publications 54, 68, and 78. Part 1 of the OIR series has been issued (ICRP, 2015), and describes the assessment of internal occupational exposure to radionuclides, biokinetic and dosimetric models, methods of individual and workplace monitoring, and general aspects of retrospective dose assessment. The following publications in the OIR series (Parts 2–5) will provide data on individual elements and their radioisotopes, including information on chemical forms encountered in the workplace; a list of principal radioisotopes and their physical half-lives and decay modes; the parameter values of the reference biokinetic model; and data on monitoring techniques for the radioisotopes encountered most commonly in workplaces. Reviews of data on inhalation, ingestion, and systemic biokinetics are also provided for most of the elements. Dosimetric data provided in the printed publications of the OIR series include tables of committed effective dose per intake (Sv per Bq intake) for inhalation and ingestion, tables of committed effective dose per content (Sv per Bq measurement) for inhalation, and graphs of retention and excretion data per Bq intake for inhalation. These data are provided for all absorption types and for the most common isotope(s) of each element. The electronic annex that accompanies the OIR series of reports contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions. Data are provided for inhalation, ingestion, and direct input to blood. The present publication provides the above data for the following elements: hydrogen (H), carbon (C), phosphorus (P), sulphur (S), calcium (Ca), iron (Fe), cobalt (Co), zinc (Zn), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), and technetium (Tc).

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.